a) Field of the Invention
The present invention relates to a fishline length measurement device for a fishing reel, and in particular to a measurement device capable of measuring an amount of feeding or winding of the fishline based on the spool rotation number with high accuracy.
b) Description of Related Art
Recently, there has been developed a fishing reel with a fishline length measurement device capable of measuring the length of a fishline fed from or wound onto the spool to make it possible to submerge a fishhook to a predetermined depth where fish exist or to determine the casting distance to a point.
Japanese Patent Kokai No. Hei. 1-307612 and U.S. Pat. No. 5,395,065, for example, disclose such a fishline length measurement device.
The fishline length measurement device disclosed in Japanese Kokai '612 includes: a sensor for detecting the speed and direction of rotation for a spool with respect a reel main body; a rotation/counter-rotation counter for up-counting or down-counting pulse signals sent from the sensor; a light-emitter for emitting a spot light onto an outer circumferential surface of the fishline wound on the spool; a diameter measuring assembly detecting light reflected from the outer circumferential surface with a sensor and converting the detected light into an electric signal which is in proportion to the diameter of the spool with the fishline wound thereon; a calculator for calculating the length of fishline fed off or wound on the spool based on the diameter data and the count; and, a display indicating the fishline length calculated by the calculator. The fishline length measurement device makes it possible to accurately measure the amount of the fishline fed from or wound onto the spool.
The fishline length measurement device disclosed in U.S. Pat. No. '065 includes: a sensor for detecting the speed and direction of rotation for a spool with respect a reel main body; a rotation/counter-rotation counter for up-counting or down-counting pulse signals sent from the sensor; a diameter measuring assembly using an ultrasonic wave beam reflected off an outer circumferential surface of the fishline wound on the spool to determine the diameter of the fishline wound on the spool; a calculator for calculating the length of fishline fed off or wound on the spool based on the diameter data and the count; and, a display indicating the fishline length calculated by the calculator.
The diameter measuring assembly in U.S. Pat. No. '065 includes a transmitter generating the ultrasonic wave beam, a receiver detecting the reflected wave beam, and a timer measuring the time lag between generating the ultrasonic wave beam and receiving the reflected wave. Then, the assembly converts the time lag into a signal which is in proportion to the diameter of the fishline wound on the spool, and the calculator calculates the fishline length based on the signal and the number of spool rotations counted during the feed or winding of the fishline.
The aforementioned fishline length measurement devices can measure the fed or wound fishline length with accuracy, however, consumption of battery power is large because the spot light or the ultrasonic wave beam is continuously generated during the feed or winding process of the fishline to measure the length. If large capacity batteries are incorporated to provide adequate power, the entire device becomes large.